The present invention relates generally to vehicle interior structures, and more particularly to an integrated steering column support system.
Typically, a steering assembly of a vehicle includes a steering column extending between a steering mechanism, for example, a steering wheel, and a torque distribution mechanism. The steering column is designed to translate rotation of the steering wheel by a vehicle operator to the torque distribution mechanism which correspondingly positions the wheels of the vehicle in accordance with the position of the steering wheel, thus steering the vehicle.
It is desired that the steering column be of a sufficient compressive, shear, and torsional strength to endure the above described usage. The steering column designed as such can have a substantial mass and thus must be properly supported within the vehicle for effective functioning of the vehicle steering assembly.
Accordingly, the steering column is supported by attachment to a cross-car structural beam located within the vehicle. The downward load resulting from the weight of the steering column is distributed through the cross-car structural beam to side walls of the vehicle where the cross-car structural beam is mounted thereto. The weight of the steering column is thereby conveyed, through the side walls, to a steel frame of the vehicle.
The cross-car structural beam is composed of steel so that it may support the weight of the steering column. This results in substantial mass within the vehicle.
The cross-car structural beam is also used to support an instrument panel assembly and an HVAC air duct system, both located about the beam. The structural beam further serves as a reaction surface for occupant protection devices such as air bags or knee bolsters.
These uses, in combination with functioning as a support for the steering column, further increase the required mass of the cross-car structural beam and thus add additional weight and materials to the vehicle.
In addition to compensating for the weight of the steering column, the vehicle structural system must accommodate for a first natural frequency and the undesirable effects thereof. The first natural frequency is a vibratory level of the vehicle structural system which, when reached, can result in vertical oscillatory displacement of the steering column within the vehicle.
The cross-car structural beam typically is relied upon in vehicle structural systems to prevent the occurrence of such displacement. This is accomplished by designing the beam to increase the first natural frequency beyond a level anticipated to be reached during various vehicle operating modes. Additional mass and materials are added to the cross-car structural beam in order to prevent the occurrence of the first natural frequency.
The additional mass and materials required of a vehicle structural system to accommodate the weight of the steering column assembly and to prevent against steering column displacement due to the first natural frequency, adds mass and thus increases the weight of the vehicle. This reduces the vehicle""s fuel efficiency, increases costs, complicates methods of manufacture, and encumbers maintenance and repair.
Accordingly, it is desirable to have a light weight steering column structural assembly that provides all of the necessary support for various vehicular applications as well as being economically efficient to manufacture and assemble.
According to the present invention, an integrated steering column structural system is provided for supporting various loads of a steering column disposed within a vehicle.
The structural system generally comprises a steering column bracket for retaining the steering column and for distributing various steering column loads throughout the vehicle. The structural system further includes a plurality of load distribution components for receiving the various loads of the steering column and ultimately distributing the load to a vehicle structural frame. The steering column bracket utilizes a plurality of pathways through which to distribute the various loads of the steering column to the load distribution components.
The integrated steering column structural system is directed toward distributing the downward load within the vehicle caused by the weight of the steering column. In addition, the structural system is designed to resist against steering column displacement caused by a first natural frequency of the vehicle structural frame, which subjects the steering column to various loadings.
The integrated steering column structural system distributes the above-mentioned loads to the various load displacement components that, in turn, distribute the loads to the structural frame of the vehicle.
Distribution of the steering column loads as described, results in each individual load displacement component bearing only a fraction of the total steering column load. Thus, the load displacement components may be of a reduced mass, requiring less material in their construction, therefore incurring less manufacturing costs and generally resulting in an overall lower weight, and a more fuel-efficient vehicle.
In one embodiment according to the present invention, the load displacement components include a structural air duct assembly disposed across the width of the vehicle proximate to a vehicle occupant compartment. The structural air duct assembly has a lower surface which mates with a first surface of the steering column bracket. The steering column bracket correspondingly has a second surface to which the steering column is mounted.
The load displacement components further include a plenum which is also mounted to the first surface of the steering column bracket. The plenum is a conventional structural element of the vehicle through which the steering column loads are distributed to the structural frame of the vehicle.
Finally, the load displacement components include an engine wall located within the vehicle between an engine and the occupant compartment. The steering column bracket has an extension portion which connects the engine wall and the steering column bracket, thereby allowing load distribution.
Thus, the integrated steering column structural system of the present invention offers three load distribution pathways by which to transfer the various steering column loads to the structural frame of the vehicle. A first load distribution pathway exists from the steering column bracket to the structural air duct assembly, the second pathway exists from the steering column bracket to the plenum, and the third pathway exists from the steering bracket to the engine wall.
In this way, a fraction of the total load exerted by the steering column is carried by each of the load displacement components. Therefore, these parts may be designed with less mass than were they to bear the entire force of the load exerted by the steering column. Polymeric materials and composite materials may be used in lieu of metals, such as steel, which are considerably more costly and less workable.
The reduction and alteration of construction materials used within the vehicle results in overall cost diminution and reduced labor allocations. Further, the steering column bracket is releasably fastened to the load displacement components within the vehicle, thus permitting ease of installation and maintenance.
The above-described and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims.